I am not sure which technology they use, but it is not possible to download paid for videos.
Youtube and the like are due a reckoning. It is still very much a wild west. For the users it will be a case of having to sign into Youtube to watch anything I suspect, you may still be able to search prior to login. That's the only way they are going to be able to meet the increasing number of regulations being introduced as the years go on. I know they are already asking users to confirm their age when watching certain videos within certain EU countries. Other sites such as Twitter and Reddit etc will all have to introduce age verification and that would require logins before you can access anything. Otherwise they cannot stop people seeing and accessing etc, or be able to meet the regulations.
The internet as we know it in terms of the giants will look very different in five/ten years.